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This paper juxtaposes existing public policies and different planning paradigms with evidence from the first wave of the COVID-19 pandemic in New York City (NYC). Zip code tabulation area (ZCTA) data for NYC are used to address four main questions: (1) How do urban density and crowding affect infection rates? (2) How does the commuting environment relate to pandemic resilience? (3) How does the allocation of points of interest within a city impact the infection rate? (4) How do evident inequalities in a city influence vulnerability during a pandemic? The presented evidence is used to demonstrate that compact, well-mixed, and decentralized cities can increase pandemic resilience due to advantageous features such as short commute times and well-distributed points of interest. At the architectural level, more resilient apartment building typologies need to be developed to mitigate the ramifications of overcrowding. This analysis also reveals significant spatial disparities and how they disproportionally affect the pandemic risk of the vulnerable communities. These findings warrant a broader discussion on how urban design and planning can mitigate inequalities and transform cities into a resilient, inclusive, and sustainable urban environment. [ABSTRACT FROM AUTHOR]

Urban form impacts the airflow patterns in cities and the resulting urban microclimate. This has significant implications for ventilation, overheating, wind chill, and safety concerns such as down drafts from skyscrapers. While Computational Fluid Dynamics (CFD) simulations are the best practice for analyzing urban airflow patterns in design, they are computationally expensive and require a high level of expertise, making them underutilized in the early design process. This paper presents a surrogate model for CFD using a Generative Adversarial Network (GAN) that can process arbitrary building geometries. The model is trained using an automated end-to-end pipeline based on Eddy3D and implemented within the Rhino and Grasshopper environment as an Open Neural Network Exchange (ONNX)-based CFD-GAN predictor. This workflow provides instantaneous simulation feedback within the design software, reduces the risk of user error, and allows for appropriate spatial resolution in early design. The CFD-GAN demonstrates promising accuracy, with a Structural Similarity Index Measure (SSIM) ranging from 75%–97% on a limited training dataset of 564 unique urban geometries. Although the model currently has limitations regarding accuracy in complex urban wake regions, we show that these are likely not of concern for outdoor thermal comfort analyses. While it cannot replace CFD in later design stages, the CFD-GAN facilitates the incorporation of urban airflow analysis in early design with minimal effort and instantaneous performance feedback. [Display omitted] • GAN surrogate model for urban CFD simulations processes arbitrary building geometries. • Automated end-to-end training pipeline utilizing Eddy3D produces modular ONNX-based CFD-GAN predictor. • CFD-GAN predictor integrated in Rhino & Grasshopper allows for seamless design workflow. • Achieved SSIMs ranging between 75%–97% based on 564 unique urban geometries. • Provides instantaneous simulation feedback for performance-driven decision-making in early urban design. [ABSTRACT FROM AUTHOR]

As global and local actors seek to address climate concerns, municipalities, regions, and countries are developing policies for the built environment to reach carbon neutrality. In most cases, however, current policies target new construction and operational carbon emissions only, thus omitting the significant carbon emission saving potential resulting from the reactivation of embodied carbon in existing buildings. This article describes the development of a high-resolution combined building stock model (BSM) and building energy model (BEM) on both building and urban scale using all residential buildings of Ithaca, NY, USA as a case study. The model offers a holistic, detailed and local perspective on operational and embodied carbon emissions, associated saving potentials at both the building and urban scale, and the linkages, trade-offs and synergies between buildings and energy use as a basis for decision-making. A circular economy (CE) in construction posited on the reuse and recycling of existing building materials, necessitates a detailed material inventory of the current building stock. However, the scale and nature of this endeavor preclude traditional survey methods. The modeling process described in this article instead engages a bottom-up data aggregation and analysis approach that combines detailed construction archetypes (CAs) and publicly available, higher-level municipal geospatial data with building metadata defining occupancy and systems to create an autogenerated, detailed 3D geometry. The resulting BSM and BEM can simulate both embodied carbon content and operational carbon emissions of individual buildings within a municipal study with minimal required input data and a feasible computational effort. This provides modelers with a new spatial and geometric fidelity to simulate holistic renewal efforts, and inform carbon neutrality policies and incentives towards the decarbonization of the built environment. [ABSTRACT FROM AUTHOR]

Outdoor thermal comfort simulation simulations rely on the mean radiant temperature (MRT) seen by pedestrians as an important input that remains difficult to compute. Especially for large urban models, computing relevant surface temperatures and radiation fluxes that make up the MRT is a daunting task in terms of simulation setup and the computational overhead. We propose a new algorithm to estimate exterior surface temperatures of building facades, roofs, and ground surfaces in an arbitrary urban 3D model. The algorithm discretizes all model surfaces and clusters them by material properties and sky and sun exposure to reduce computational complexity. The model setup is fully automated, and the algorithm is implemented in the popular Rhino3d CAD environment. We demonstrate the accuracy of the algorithm by comparing both the resulting external surface temperatures against a high-fidelity simulation and the final MRT against real-world measurements. We report an RMSE of 1.8 °C and 2.0 °C, respectively, while reducing simulation times by a factor of ~80. Envisioned applications of the algorithm range from rapid microclimate simulations in fast-paced urban design processes to large scale urban comfort evaluation of existing cities. • New algorithm to predict exterior surface temperatures and MRT in an arbitrarily complex urban 3D model. • The algorithm is utilizing K-Means clustering to reduce simulation times by a factor of 80. • We report an RMSE of 1.8°C for surface temperature predictions of a full year. • Importance of long-wave radiation exchange is analyzed. • Largest heterogeneity in external surface temperature is reported for horizontal clusters close to obstacles and south-facing clusters. [ABSTRACT FROM AUTHOR]

Solar access is a crucial factor for the wellness and comfort of building occupants and for the development of the urban fabric. Most countries implemented regulatory frameworks that aim to guarantee appropriate access to sunlight into buildings. The solar envelope is a method that allows to determine the maximum buildout volume that guarantees solar access of neighboring buildings. Computer design tools have been developed to facilitate the automatic creation of solar envelopes. However, most of the tools have limitations when complex regulations need to be taken into account. The presented research develops an alternative computational method to generate solar envelopes to be used for different ordinances and particularly efficient in dense urban environments. Results show that the proposed method permits to obtain larger building masses than the conventional method, and to automate the generation of envelope variations, useful for assessing building performance and form selection in the early design stage. • The presented research develops an alternative method to generate solar envelopes named the Reverse Solar Envelope (RSE). • Differently than the conventional method the RSE method can be used in relation to different solar access ordinances. • The RSE method permits to generate larger solar envelopes than the conventional method especially in urban environments. • The workflow of the RSE generates automatically a number of solar envelopes for evaluation of building form alternatives. • The RSE method permits to automate the performance analysis process to improve building comfort and environmental impact. [ABSTRACT FROM AUTHOR]

• Annual outdoor thermal comfort evaluation workflow is introduced. • 60 typology and density scenarios in three hot climatic contexts were evaluated. • Annual energy balance and outdoor thermal comfort results were recorded iteratively. • The impact of urban form on energy performance and outdoor comfort is discussed. • This method helps integrate environmental quality considerations in urban design. With the rise of awareness of health and well-being in cities, urban environmental analysis should expand from energy performance to new environmental quality-based considerations. The limited potential to annually evaluate outdoor thermal comfort, predominant among these considerations, has restricted the exploration of the interrelations between urban morphology and annual energy performance. This study aims to bridge this gap by capitalizing on the new capabilities of Eddy3D – a Grasshopper plugin which enables effective calculations of hourly microclimatic wind factors via OpenFOAM which in turn are used to generate annual outdoor thermal comfort plots. Using this method, a parametric study was conducted for different typology and density scenarios in three different hot climatic contexts in Israel. The automated analytical workflow evaluated a total of 60 design iterations for their energy balance, outdoor thermal comfort autonomy (OTCA) and self-shading levels using the shade index. The high correlation found here between the annual shade index and the OTCA, across all climatic contexts, shows the potential of the shade index to serve as an effective indicator, in these contexts, for comparative or optimization outdoor comfort studies. Further results are both the superiority of the courtyard typology in both energy and outdoor comfort studies, and the contrasting impact of higher density on the annual energy balance (lower performance) and outdoor thermal comfort (higher performance) in hot climates. The annual plots of both the energy balance and OTCA reveal various seasonal and monthly trends in the three different climatic zones which can lead to localized and seasonal urban design strategies. [ABSTRACT FROM AUTHOR]